Dr. Justin Silverstein, DHSc, FASNM, FASET

Harshal Shah, Faina Ablyazova, Annabell Alrez, A. Gabriella Wernicke, Morana Vojnic, Beril Yaffe, Randy S. D'Amico

Asleep Motor speech mapping in patients who cannot tolerate awake surgery

The transpsoas lateral lumbar interbody fusion (LLIF) technique is an effective alternative to traditional anterior and posterior approaches to the lumbar spine. The advantages of the far lateral lumbar approach are well documented, however iatrogenic injuries to the lumbar plexus are the most commonly reported post-operative complications. The most feared of these complications is a high-grade femoral nerve injury which can be debilitating. Suspected mechanisms of femoral nerve injury include,… Show more

The transpsoas lateral lumbar interbody fusion (LLIF) technique is an effective alternative to traditional anterior and posterior approaches to the lumbar spine. The advantages of the far lateral lumbar approach are well documented, however iatrogenic injuries to the lumbar plexus are the most commonly reported post-operative complications. The most feared of these complications is a high-grade femoral nerve injury which can be debilitating. Suspected mechanisms of femoral nerve injury include, compression, stretch, and disrupted vascular perfusion, all of which are suspected to be related to excessive or prolonged surgical retraction. New methods of monitoring femoral nerve function have been evolving and gaining greater acceptance as multiple independent groups have reported similar promising findings. We present our results from a multi-center study conducted over the course of 3 years using a multimodality femoral nerve monitoring protocol that includes saphenous nerve somatosensory evoked potentials (SnSSEP), motor evoked potentials with quadriceps muscles recordings (MEPq) and free-running EMG (EMG) to assess femoral nerve function during surgical retraction. Show less

Awake craniotomy is advocated for the resection of supratentorial low-grade gliomas (LGG). The combination of neurophysiological electrical mapping techniques and performing the craniotomy awake has demonstrated increased total and supratotal resection of LGG, as well as increased overall survival rates. We present an illustrative case where the patient's gross motor function deteriorated during the resection of a LGG and mapping techniques using the phase reversal technique and Taniguchi… Show more

Awake craniotomy is advocated for the resection of supratentorial low-grade gliomas (LGG). The combination of neurophysiological electrical mapping techniques and performing the craniotomy awake has demonstrated increased total and supratotal resection of LGG, as well as increased overall survival rates. We present an illustrative case where the patient's gross motor function deteriorated during the resection of a LGG and mapping techniques using the phase reversal technique and Taniguchi direct cortical stimulation technique while the patient was awake proved to be valuable in determining continuity of the corticospinal tracts. Show less

In this small series, we were able to acquire motor evoked potentials in 100% of
patients when recorded from the urethral sphincters using a urethral catheter
with electrodes built into it. USMEPs can be attempted in surgeries that put the
function of the pelvic floor at risk. Patients 4 and 7 are illustrative cases that
may show the prognostic value in using USMEPs; however, more study is
needed to establish better statistical methods, better modality efficacy, and a
better… Show more

In this small series, we were able to acquire motor evoked potentials in 100% of
patients when recorded from the urethral sphincters using a urethral catheter
with electrodes built into it. USMEPs can be attempted in surgeries that put the
function of the pelvic floor at risk. Patients 4 and 7 are illustrative cases that
may show the prognostic value in using USMEPs; however, more study is
needed to establish better statistical methods, better modality efficacy, and a
better understanding of intraoperative countermeasures that may be employed
when an alert is encountered to prevent impending neurological sequelae.

Reference: Jahangiri, F., Silverstein, J., George, Z., Al Eissa, S. (2018). Motor Evoked Potential Recordings From Uretheral Electrodes. Abstract presented at the ASNM Annual Meeting [Orlando, FL] February 2018. Show less

C5 neuropraxia is a known, poorly understood complication of cervical spine surgery and has a reported incidence as high as 30% in some studies. Weakness of the deltoid and biceps muscles present immediately postoperatively or in a delayed fashion. The exact etiology remain elusive and controversy regarding the efficacy and utility of neuromonitoring for intraoperative detection of these injuries exist. We describe a novel approach to monitoring for C5 nerve root palsies by evaluating motor… Show more

C5 neuropraxia is a known, poorly understood complication of cervical spine surgery and has a reported incidence as high as 30% in some studies. Weakness of the deltoid and biceps muscles present immediately postoperatively or in a delayed fashion. The exact etiology remain elusive and controversy regarding the efficacy and utility of neuromonitoring for intraoperative detection of these injuries exist. We describe a novel approach to monitoring for C5 nerve root palsies by evaluating motor evoked potential recordings (MEP) and spontaneous electromyographic recordings (s-EMG) from the three heads of the deltoid muscles along with standard MEP/EMG target muscle recordings contemporaneously. Show less

Additional Authors: William Goliber, CNIM; David Kramer, MD; David Bomback, MD; J. Reynolds; N. Goldthwaite; Hieu Ball, MD; Bruce Bizzini, CNIM

BACKGROUND CONTEXT:
Somatosensory evoked potentials (SSEPs) are effective in detecting upper extremity positional injuries; however, causal factors for which patient population is most at risk are not well established.
PATIENT SAMPLE:
398 patient charts and intraoperative neurophysiological monitoring data from patients who underwent thoracolumbar and lumbosacral spine surgery were reviewed in a consecutive sequence from 2012 to 2013.
OUTCOME MEASURES:
Adverse events (AE) with… Show more

BACKGROUND CONTEXT:
Somatosensory evoked potentials (SSEPs) are effective in detecting upper extremity positional injuries; however, causal factors for which patient population is most at risk are not well established.
PATIENT SAMPLE:
398 patient charts and intraoperative neurophysiological monitoring data from patients who underwent thoracolumbar and lumbosacral spine surgery were reviewed in a consecutive sequence from 2012 to 2013.
OUTCOME MEASURES:
Adverse events (AE) with the upper extremity SSEP recordings were compared to the independent variables, sex, positioning, length of procedure, and body habitus.
METHODS:
Thoracolumbar and lumbosacral spine surgeries using contemporaneous ulnar and median nerve SSEPs were reviewed. The one-way analysis of variance (ANOVA) test, Chi-square, and independent samples t test were used to determine statistical significance in having an upper extremity SSEP AE to the aforementioned independent variables.
RESULTS:
The sample consisted of 209 males (52.5 %) and 189 females (47.5 %) (n = 398). AE to the upper extremity SSEP was seen in 44 patients. Sex was found to be statistically significant for isolated ulnar nerve AE (P ≤ 0.001) with males being most at risk (87.5 %). AE for isolated median nerve SSEP was statistically significant for supine and prone positions (P = 0.043). Length of procedure was statically significant for isolated ulnar nerve SSEP AE (P = 0.039). BMI was statistically significant for generalized upper extremity SSEP AE (P = 0.016), as well as isolated ulnar SSEP AE (P = 0.006), isolated median SSEP AE (P ≤ 0.001) and contemporaneous median and ulnar SSEP AE of the same limb (P ≤ 0.001).
CONCLUSION:
Sex, patient positioning, length of procedure, and BMI are determinants for upper extremity neural compromise during thoracolumbar and lumbosacral spine surgeries. Show less

Somatosensory evoked potentials (SSEPs) are a valuable tool for assessing changes in peripheral nerve pathways caused by patient positioning during spinal surgeries. These changes, when left undiagnosed, may lead to postoperative neurological sequelae. Why an upper extremity SSEP attenuates due to positioning is not necessarily clear and can be multifactorial, affecting the peripheral nerves or elements of the brachial plexus. A conduction block can occur at any point along the course of the… Show more

Somatosensory evoked potentials (SSEPs) are a valuable tool for assessing changes in peripheral nerve pathways caused by patient positioning during spinal surgeries. These changes, when left undiagnosed, may lead to postoperative neurological sequelae. Why an upper extremity SSEP attenuates due to positioning is not necessarily clear and can be multifactorial, affecting the peripheral nerves or elements of the brachial plexus. A conduction block can occur at any point along the course of the nerve secondary to entrapment, compression, and ischemia. These mechanisms of injury may be caused by extreme body habitus, the length of the procedure, or the patient’s metabolic underpinnings. The goal of neuromonitoring for positional injury is to predict and prevent both peripheral nerve and brachial plexus injuries. Using ulnar and median nerve SSEPs contemporaneously may lead to better identification of compromised structures when an SSEP change to one or both of the nerves occurs. The investigators provide four case reports where intraoperative SSEP assessment of contemporaneous ulnar and median nerves prevented postoperative upper extremity neural deficits. Show less

Abstract presentation 4/8/16 - Las Vegas Nevada

Abstract accepted for presentation at ISASS16 - Las Vegas Nevada 4/6/16

ASETnews Volume 39, Number 2

Chosen as an editor's choice for re-publication. 1st published in November 2014

There has been a major trend in surgery towards less invasive procedures performed through smaller surgical apertures. Smaller surgical openings are associated with decreased visualization, and surgeons must rely more on intraoperative tools including fluoroscopic imaging and motor nerve mapping techniques to assess their relative anatomical position and proximity to neural structures respectively. In retroperitoneal lateral lumbar interbody fusion (LLIF) procedures, the surgeon must establish… Show more

There has been a major trend in surgery towards less invasive procedures performed through smaller surgical apertures. Smaller surgical openings are associated with decreased visualization, and surgeons must rely more on intraoperative tools including fluoroscopic imaging and motor nerve mapping techniques to assess their relative anatomical position and proximity to neural structures respectively. In retroperitoneal lateral lumbar interbody fusion (LLIF) procedures, the surgeon must establish a safe surgical corridor to access the disc space by traversing through the substance of the psoas muscle while avoiding damage to the lumbar plexus. Surgeons utilize Triggered EMG (T-EMG) using a monopolar electrical probe to detect the presence and proximity of lumbar plexus elements in the surgical field. A detailed understanding of the functional anatomy of the lumbar plexus and an appreciation of anatomical variants is essential to understanding how to effectively map the lumbar plexus. Show less

ASETnews Fall 2015 Volume 39 Number 3 Pg 16-17

Presented during the MIS complications session during the 2014 ISASS meeting in Miami Fl.

SPINE Volume 39 , Number 15 , pp 1254 - 1260
©2014, Lippincott Williams & Wilkins

Silverstein, J. (2013). Does anodal blocking occur in routine intraoperative SSEP stimulation? ASETnews. (37)4:17-21

This was presented as a BEST paper at ISASS13 in Vancouver CA. This is an abstract published in the International Society for the Advancement of Spinal Surgery (ISASS) official abstract book.

This is a sneak peek interview I did with ISASS

This is an abstract publication, published in the society's proceedings